The International Monetary Fund warned that the world economy will be weaker than expected next year and possibly fall into a serious slump.

The IMF said policy makers in the United States and Europe must make the right decisions on the economic problems facing their countries.

Europe is already in a recession, and its leaders are still trying to get its international debt crisis under control.

Politicians in Washington must also reach an agreement on the budget cuts and tax hikes by the end of the year. If they don't, economists have warned the United States could fall back into recession.